Image sensors are usually operated to sense light. Typically, the image sensors include complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) and charge-coupled device (CCD) sensors, which are widely used in various applications such as digital still camera (DSC), mobile phone camera, digital video (DV) and digital video recorder (DVR) applications. These image sensors absorb light and convert the sensed light into digital data or electrical signals.
When a trend of electronic products including image sensors, such as mobile phone cameras, is developed toward more and more compact design, camera modules of the mobile phone cameras need to be scaled down. However, as the thickness of the mobile phones keeps shrinking down, it is more difficult to produce the camera modules with a desired thickness for the compact mobile phone camera.
Accordingly, while conventional image sensors may have been generally adequate for certain purposes, they have not been entirely satisfactory in every aspect.